This invention relates to a print-job system and methodology. In particular it relates to such a system and methodology which offer special control over the flow of successive document pages for proper collation, where different pages in the job have followed different, respective flow paths during implementation of the job. The term “print job” and the like as used herein is intended to refer generally to any imaging job out of which printed pages emerge for assembly into a final document.
A good illustration (from many which could be chosen) of where practice of the present invention offers special utility can be visualized in the context of a document imaging job, such as a document scanning, copying and/or printing job, wherein certain pages are entirely black-and-white pages, and other pages are entirely, or partially, color-containing pages. In such a job, it is typical that purely black-and-white pages follow one processing flow path, whereas pages containing color follow another flow path.
Where document imaging jobs are thus handled as split jobs for various reasons, proper reuniting of pages in the correct order during collation is of course necessary. Such reuniting has been handled in the past by a number of different techniques which are, for one reason or another, either relatively complex, or somewhat expensive to implement, or both.
The present invention addresses this issue with an approach which focuses upon incorporating, into job-specific, page-description (PDL) language, page-handling, or page-feed, instructions which include instructions that specify different “plural-stream” sources as direct feed sources for a job-page collator. Very specifically, in a job wherein two flow streams, or paths, are followed, one by black-and-white pages, and other by color-containing pages, two different path-associated feed “trays”, such as a pre-fuser tray, and a post-fuser tray, may be employed as sources for the “feeding or pulling” of pages into an associated collator. Where, as in many documents, the black-and-white pages outnumber the color-containing pages, in accordance with practice of the present invention, the black-and-white pages will follow the pre-fuser path/tray route, and the color-containing pages the post-fuser path/tray route.
Utilizing the present invention, by incorporating such page-feed instructions in the PDL associated with a specific job, complexities which attend various prior art practices are avoided, as are elevated handling expenses. With PDL page-feed instructions embedded within the “boundaries” of a given document imaging job, these instructions are implemented after interpretation by an appropriate PDL interpreter, which then effectively controls respective-path, page-feed, or page-flow, activities. This is all accomplished in accordance with appropriate timing so that correct, next-adjacent, successive pages are fed in the right order to a collator.
In this context, the present invention implements a unique practice whereby virtual, or ghost pages, are created, especially in the pre-fuser feed line of document pages. These ghost pages act as surrogates for certain real pages which are following another flow path, such as pages which follow a color-imagery flow path. When a ghost page appears in a path, a real page is pulled, or fed, from the other path, and the result is a properly collated final document. From the point of view of the flow of document pages through and along the pre-fuser path, the presence of such ghost pages causes that flow path to see, effectively, a continual flow of document pages, notwithstanding the fact that there is actually an interleaving kind of flow taking place between two or more document page paths, all accommodated by the presence of such properly timed ghost pages under the control of the PDL page-feed instructions.
The various features and advantages of the invention just suggested will become more fully apparent as the description which now follows is read in conjunction with the accompanying drawings.